not so cold, its temperature before it comes out again must be reduced to 28°, or whatever be the average 

 temperature of the outer but surface current. 



Moreover, if it be true as some philosophers have suggested, that there is in the depths of the ocean a line from 

 the equator to the poles, along which the water is of the same temperature all the way, then the question may be 

 asked : should we not have in the depths of the ocean, a sort of isothermal floor, as it were, on the upper side 

 of which all the changes of temperature are due to agents acting from above, and on the lower side of which 

 the changes, if any, are due to agents acting from below? 



This under Polar current water then, as it rises to the toj), and is brought to the surface by the agitation 

 of the sea in the Arctic regions, gives out its surplus heat and warms the atmosphere there till the temperature 

 of this warm under current water is lowered to the requisite degree for going out on the surface. 



And the heat that it loses in falling from its normal temperature, be that what it may, till it reaches the 

 temperature of 28°, is so much caloric set free in the Polar regions to temper the air and mitigate the climate 

 there. Now is not this one of those modifications of climate, which may be fairly traced back to the effect of 

 the saltness of the sea in giving energy to its circulation? 



Moreover, if there be a deep sea in the Polar basin which serves as a receptacle for the waters broucht 

 into it by this under current which, because it comes from towards the equatorial regions, comes from a milder 

 climate, and is, therefore, warmer, we can easily imagine why there might be an open sea in the Polar regions ; — 

 why Lieut. De Haven in his instructions was directed to look for it ; and why, both he, and Capt. Penny of 

 one of the English searching vessels, found it there. 



And in accounting for this Polynia, we see that its existence is not only consistent with the hypothesis with 

 which we set out touching a perfect system of oceanic circulation, but that it may be ascribed, in a great degree 

 at least, if not wholly, to the effect produced by the salts of the sea upon the mobility and circulation of its waters. 



Here then is an office which the sea performs in the economy of the universe by virtue ©fits saltness, and 

 which it could not perform were its waters altogether fresh. And thus philosophers have a clue placed in their 

 hands which will probably guide them to one of the many hidden reasons that are embraced in the true answer 

 to the question, " why is the sea salt ? " 



But we find in sea water other matter besides common salt. Lime is dissolved by the rains and the rivers, 

 and emptied in vast quantities into the ocean. Out of it, coral islands and coral reefs of great extent — marl beds, 

 shell banks, and infusorial deposits of large dimensions, have been constructed by the inhabitants of the deep. 



These creatures are endowed with the power of secreting, apparently for their own purposes only, solid 

 matter which the waters of the sea hold in solution. But this power was given to them that they also mio-ht 

 fulfil the part assigned them in the economy of the universe. For to them, probably, has been allotted the im- 

 portant office of assisting in giving circulation to the ocean, and of helping to regulate the climates of the earth. 



The better to comprehend how such creatures may influence currents and climates, let us suppose the ocean to 

 be perfectly at rest ; — that throughout, it is in a state of complete equilibrium; — that, with the exception of those 

 tenants of the deep which have the power of extracting from it the solid matter held in solution, there be no agent in. 



